test: v4l2_videodevice: buffer_cache: Use DRM pixel format

The pixel format used in the stream configuration is from V4L2 but
should be from DRM, fix it.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

test/v4l2_videodevice/buffer_cache.cpp

@@ -142,7 +142,7 @@ public:
 		const unsigned int numBuffers = 8;
 
 		StreamConfiguration cfg;
-		cfg.pixelFormat = V4L2_PIX_FMT_YUYV;
+		cfg.pixelFormat = DRM_FORMAT_YUYV;
 		cfg.size = Size(600, 800);
 		cfg.bufferCount = numBuffers;